Internal combustion engine



July 4, 1967 L. w. LLEWELLYN INTERNAL COMBUSTION ENGINE 4 Sheets-Sheet 1 Filed March 29, 1965 INVEN TOR LEOPQLD W- LLEWELLYN July .4, 1967 L. w. LLEWELLYN .INTERNAL COMBUSTION ENGINE 4 Sheets-Sheet 2 Filed March 29, 1965 INVENTOR LEOPOLD W. LLEWELLYN July 4, 1967 w. LLEWELLYN INTERNAL COMBUSTION ENGINE 4 Sheets-Sheet 5 Filed March 29. 1965 INVENTOR LEOPOLO W. LLEWELLYN fa f July 4, 1967 L. w. LLEWELLYN 3,329,134

I NTERNAL COMBUSTION ENGINE Filed March 29, 1965 4 Sheets-Sheet 4 INVENTOR LEOF'OLD W. LLEWELLYN ZHJ United States Patent O ice 3,329,134 INTERNAL CGMBUSTION ENGINE Leopold W. Llewellyn, 4740 Southlawn Drive, Burnaby, British Columbia, Canada Filed Mar. 29, 1965, Ser. No. 443,282 7 Claims. (Cl. 12355) The present invention relates to improvements in the design of piston-type motors and more particularly to small size gasoline powered engines.

The objects of the invention are to provide a motor with a greatly reduced number of working parts, to provide an arrangement of the parts which will simplify and compact the engine so that it is especially suitable for use on power mowers, chain saws and the like and to reduce the torsion imposed upon the crank shaft and the stress placed on other engine parts to a point where lightweight and relatively inexpensive components may be used.

A further object is to provide each power cylinder with a separate charging-scavenging cylinder resulting in increased engine efficiency.

A still further and important object is to journal the crank shaft in the pistons rather than in the crank case as in a conventional motor. This avoids the use of connecting rods and results in an unusual crank shaft motion from which mechanical advantage is derived.

These objects and other advantages provided by the present engine design will be described in detail in the following specification and be shown in the accompanying drawing.

Referring to the drawings:

FIGURE 1 is a reduced scale side elevation of the invention.

FIGURE 2 is a section taken on the line 2-2 of FIG. 1 and showing the power pistons in mid-position,

FIGURE 3 is a section taken on the line 3-3 of FIG. 1 and showing the left power piston in top dead centre position.

FIGURE 4 is a side elevation of the power cylinder liner and showing a part of the crank case.

FIGURE 5 is a section taken on line 5*5 of FIG. 4 with part of the crank case broken away.

FIGURE 6 is an elevation of the crank shaft and charge piston assembly, part in section.

FIGURE 7 is a section taken on line 77 of FIG. 2.

FIGURE 8 is a section taken on line 88 of FIG. 2.

FIGURE 9 is a diagram showing the tumbling motion of the crank shaft.

FIGURES 10 to 17 are diagrammatic views showing one complete cycle of the two cycle engine.

The present motor has a crank case 10 in which two horizontally opposed power cylinders 11 and two vertically opposed charge cylinders 12 are formed. A base plate 14 supports the crank case and also serves as an end closure for the lower cylinder 12. The uppermost of the charge cylinders is fitted with a suitable head 15. Heads 16 are bolted to the power cylinders and are fitted with conventional spark plugs 17. The cylinders 11 will herein be referred to as left and right cylinders having reference to FIG. 3. Walls and heads of the power cylinders are provided with cooling fins.

. At the intersection of the cylinders 11 and 12 a chamber 20 is defined within the crank case. The power cylinders are fitted with :a common liner 21 which extends across the chamber 20. Side openings 22 in the cylindrical liner 21 provide access to the crank case chamber. For each power cylinder, the liner has an encircling row of suitably spaced ports made up of intake ports 24, exhaust ports 25 and suction ports 26. In FIG. 5 it is shown that the power cylinder walls have duplicate openings 3,329,134 Patented July 4, 11967 corresponding to the liner ports, however these openings are not separately numbered for the sake of brevity. Reference herein to the liner ports will be understood to include the wall openings as well. The ports 24 and 26 communicate with passages 27 formed in the crank case 10. One of these passages extends around the left power cylinder to the top of the upper charge cylinder. The lower charge cylinder and the right power cylinder are similarly connected by the second passage 27. The exhaust ports 25 are connected by a manifold or short length of pipe 28 either to a muflier or directly to atmosphere.

The case 10 of this two cycle motor encloses a crank shaft 30, see particularly FIG. 6. The shaft 30 has :a single crank pin 31, which is disposed within the liner 21, and offset webs 32 which project through the liner openings 22. Two aligned crank pins 33 are provided on the projecting ends of the webs and these pins have extensions 34.

Mounted in the liner 21 are two identical power pistons 35, desirably aluminum, which are secured together in end-to-end relation by bolts '36. The abutting ends of the pistons 35 are recessed to support a bearing 37 in which the pin 31 of the crank shaft is journalled. Thus, the power pistons are bolted directly to the crank shaft to avoid the use of connecting rods. The sides of the connected pistons 35 are recessed as at 38 and the ends of said pistons have upper and lower larcuate recesses 39 and 40 respectively.

It is seen that the power pistons secured to one another at abutting ends as described above efliectively constitute a single piston which is double acting, the single piston having two elements, piston heads being at outer ends of the elements. This is also effectively so with respect to the charge pistons below described.

Referring now to FIG. 6, the numeral 42 generally indicates the charge piston assembly. This assembly consists of two identical piston elements 43 which are slidably mounted in the cylinders 12. Since the pistons 43 are preferably aluminum they are fitted with a steel sleeve 44. The opposing ends of the charge pistons have domed recesses 45 which conform to the curvature of the liner 21. Connecting the pistons 43 together as a unit are two spaced slide blocks 47 which are secured to said elements by bolts 48. The rectangular blocks 47 have horizontally aligned bearings 49 in which the pins 33 of the crank shaft rotate. A pair of transversely spaced vertically extending guides 52 are provided in the crank case 10, one pair on each side of the chamber 20 so as to form extensions of this chamber, and the slide blocks are mounted one in each of said pair of guides. In this manner the assembly 42 is connected to the crank shaft and is slidably supported by the blocks 47 within their guides and also by the pistons 43 within their cylinders 12.

It should be noted the opposing edges of the slide blocks are spaced apart a distance only slightly greater than the minimum width of the power pistons 35 and also that said edges are recessed to receive the crank webs 32. As the assembly 42 reciprocates, the recessed edges of the slide blocks move through the openings 22 in the liner and the recesses 38 in the power pistons. At the end of each stroke a part of the liner 21 enters the domed recesses 45 in the charge pistons. Thus, the overall dimensions of the assembly 42 are materially reduced and this contributes to the compactness of the engine.

The crank case 10 is provided at one end with a circular body portion 55, see particularly FIGS. 2 and 7. One extension 34 of the shaft 30 projects into the portion 55 where it is fitted with a pinion 56, the pinion being eccentrically disposed with respect to the common axis of the aligned crank pins 33. The pinion teeth are cut on the outer peripheral edge only of the gear blank, the inner edge being shaped to provide an inwardly projecting flange 58 having an outside diameter equal to and aligned with the pitch circle of said teeth. Bolted to the vertical flange of the portion 55 is a flanged housing 60 having an integral sleeve bearing 61. A drive shaft 62 is mounted in the sleeve bearing and this shaft has a concentric internal ring gear 63 which is engaged by the pinion 56. The portion 55, housing 60 and the shaft 62 are all concentric about the longitudinal axis A of the crank case 10. A concentric flywheel 64 may be mounted on the outer end of the shaft 62.

The opposite end of the crank case also has a similar concentric body portion 65 into which the other extension 34 of the shaft 30 projects. This outwardly projecting shaft extension is fitted with an eccentric thrust ring 66 which, in FIG. 8, is shown to have a number of openings 67. Secured to the portion 65 is an end plate 68 having a central opening 69. Since the present motor has its flywheel 64 at the opposite end, a suitable carburetor 70 may conveniently be bolted directly to the plate 68 with its fuel delivery throat in communication with the openings 69 and 67.

It will be noted the weight of the two power pistons 35 is equal to the weight of the charge piston assembly 42. Thus, the power pistons and assembly 42 are in balance and these two equal masses then have a simple harmonic motion along axes indicated by the letters B and C respectively, see FIGURES 2 and 9, the axes being disposed at 90 to each other. The crank shaft pins 33 are partly counterbalanced by the eccentric pinion 56 and thrust ring 66. In order to give added uniformity to the irregular crank shaft motion, balance weights 72 are provided. FIGS. 7 and 8 show that the weights 72 consist of a band of hard wearing metal which is shaped to provide semi-circular and outer and inner walls 73 and 74. The space between these walls and their connecting members is filled with a heavy metal, desirably babbitt. The outer wall 73 of one weight conforms to the curvature of the portion 55 while the inner wall 74 has the same radius as the circular flange 58 of the eccentric pinion. The other weight 72 similarly fits the portion 65 and the thrust ring 66. It is noted the balance weights are unattached and are free to slide relative to their enclosing body portions and the pinion 56 or thrust ring 66 as the case may be. These last mentioned members drive the balance weights around within the body portions as the crank shaft rotates, thus reducing engine vibration.

The crank shaft motion is an unusual one and may best be understood with reference to FIG. 9. In this figure it will be seen how the axis B of the power cylinders and the axis C of the charge cylinders intersect at right angles and that the point of intersection is on the crank case axis A. Obviously the reciprocating power pistons 35 will move the crank pin 31 back and forth along the axis B. The aligned pins 33 are also moved by the assembly 4-2 along straight line paths disposed parallel to the axis C. Since the stroke of the power pistons is equal to that of the charge pistons, the crank pins 33 travel alternatively above and below the horizontal plane of the axis B. This straight line movement of the pins 31 and 33 causes the crank shaft to rotate about an axis D which obviously extends through the webs at mid-point. Assuming that initial movement of the pistons 35 is to the left of FIG.

' 9, then rotation of the crank shaft is clockwise through 360 for each two complete strokes of said pistons. As this clockwise rotation of the crank shaft about axis D .takes place, axis D itself is moved counter clockwise about a circular path equal in diameter to the throw of the crank shaft or one-half a stroke of the pistons.

. As previously mentioned the present internal combustion engine is two cycle i.e. each piston completes two strokes for each revolution of the crank shaft. During 360 rotation of this shaft each piston 43 executes first an intake stroke then a charge stroke and each piston 35 executes a compression stroke followed by a power stroke. The carburetor is under constant suction by either one or the other of the pistons 43 and the fuel-air mixture is drawn into the chamber 20 through the openings 69 and 67 thence through the adjacent pair of guides 52 above and below their reciprocating slide block 47. As the power pistons 35 move back and forth in their cylinders, the several ports in the liner 21 are covered or uncovered to control the flow of fluid from the chamber 20 to the charge cylinders 12 and from these cylinders to the power cylinders 11. For example, the suction ports 26 are open as long as they are in register with the elongated recesses 38 which is during a greater part of the travel of the power pistons. The intake ports 24 and exhaust ports 25 are open only at the extreme limit of travel of the power pistons at which time they communicate with the interior of the cylinders 11 through the arcuate recesses 39 and 40 respectively, see FIG. 3. Thus the amount of fuel mixture delivered to the cylinders is accurately and positively controlled without being influenced by the surging and uneven distribution of a manifold system. It will be apparent from the drawing that the upper cylinder 12 charges the left cylinder 11 (FIG. 3) and the lower cylinder 12 charges the right cylinder 11. Obviously the spark plugs 17 are adapted to be fired at appropriate intervals by a conventional timing device, not shown.

Referring now to FIGS. 10 to 17, the operation of the motor is as follows: As the upper piston 43 descends to complete its intake stroke (FIGS. 10 to 14), fuel is drawn through the open suction ports 26 and the passage 27 into the upper cylinder 12. A moment after the bottom dead centre position of FIG. 14 is reached the ports 26 are closed and the upper piston 43 ascends initially to precompress the charge (FIGS. 14 and 16). Just before the position of FIG. 16 is reached, the ports 24 and 25 are opened and the still rising piston 43 injects the precompressed charge into the left cylinder 11. As the upper piston 43 continues to rise and approaches top dead centre (FIG. 10) at the end of its charging stroke, all the ports are closed with a very small amount of the fuel mixture remaining in the charge cylinder. This small charge serves as a cushion for the piston so that it is able to stop and reverse its direction of travel without knocking or imposing undue strain on the motor parts.

FIGURE 16 shows the position of the several parts at the moment the left power piston 35 is about to start its compression stroke. Just before this position is reached the ports .24 and 25 are opened whereupon the charge from the upper charge cylinder is admitted to the left power cylinder. The incoming charge entering through the ports 24 sweeps through the cylinder and drives the burned gases of the previously fired charge out through the ports 25. The left piston 35 now moves from the FIG. 16 position to FIG. 17 and FIGS. 10 and 11 to the top dead centre position of FIG. 12. Just before the FIG. 12 position is reached the spark plug 17 is fired to ignite the charge and drive the left piston 35 through its power stroke.

All the above described movements of the charge and power pistons take place during onecomplete revolution of the crank shaft. During this time the right power cylinder is charged by the action of the lower charge piston so that there are two power strokes for each crank shaft revolution. As one power piston executes its power stroke the other power piston moves through its compression stroke, the crank shaft pins at the moment ofthe firing of the charge substantially are in the horizontal plane of the axis B. For this reason the force of the fuel explosion is transmitted to the crank shaft at a time when it is receiving its maximum support from the slide blocks which are in mid-stroke position in their guides and also from other engine parts. This greatly relieves the torsional stress which normally is imposed upon a crank shaft and of course, eliminates the side strain a conventional piston is subjected to when connecting rods are employed. By operating the reduced number of working parts in this manner maximum use is made of the fuel energy resulting in a highly efiicient engine. At least part of this efficiency can be attributed to the means whereby one power piston is moved through its compression stroke by the directly opposed power piston during its power stroke. The two connected power pistons themselves transmit the force of the explosion into a compressive force without the need of the usual power consuming parts to connect the pistons.

The present engine has been described as two-cycle but the same basic design is equally as well adapted for use on a four cycle motor. If desired the two or four cycle motor could have one power and one charge cylinder arranged in the form of a V. Also the design lends itself extremely well to motors having banks of cylinders, the pistons of which drive a common crank shaft. The same basic design can be adapted for use in diesel or steam engines, air-compressors, air motors and similar pistontype mechanisms of any desired size.

As previously mentioned the engine is extremely small and compact for the large horsepower it will develop but other advantages are derived from this particular design as well. For example, the amount of energy required to be expended in charging the power cylinder is reduced due to the close proximity of the charge and power cylinders and the direct connection therebetween. The actual charging of a power cylinder takes place only at the moment its power piston is hovering in virtual idleness near bottom dead centre. The incoming charge then is not opposed by piston movement towards top dead centre as it is in many other motors.

The overall length of the two opposed power cylinders is only slightly greater than three times the stroke of the power pistons. With such an arrangement the weightpower ratio is excellent which makes the engine suitable for use on chain saws, power mowers and other devices having such power requirements.

Securing the charge and power pistons to the crank shaft without the use of connecting rods not only compacts the motor but gives certain mechanical advantages as well. The resulting motion of the crank shaft and the eccentric pinion to internal ring gear drive between said shaft and the output shaft of the motor gives added leverage which increases the torque. When a power piston is near mid-stroke it is travelling at its maximum speed and exerting its greatest force on the crank shaft. At this time the tooth of the pinion 56 which is presently engaging the ring gear 63 is on the opposite side of the crank shaft to the crank pin 31. This provides a leverage advantage equal to the ratio between the throw of the crank shaft and the distance the point of tooth contact projects beyond the fulcrum, i.e., the common axis of the pins 33. Assuming this ratio is 2 to 1 and that the pinion 56 and gear 63 ratio is 3 to 2, then the actual gear reduction of the power transmission is 3 to 1.

The crank shaft motion is such that each piston is virtually at rest in the endmost 14.65% of its travel. During the remaining 70.70% or mid-portion of the piston stroke maximum velocity is reached and the above mentioned 2 to 1 leverage advantage remains almost unchanged during this fastest portion of the power pistons travel.

What I claim is:

1. An internal combustion engine having a power piston reciprocating within aligned power cylinders, a charge piston reciprocating within aligned charge cylinders, paths of the reciprocations intersecting and being mutually perpendicular, an output shaft having an axis, the power piston being operatively connected to the output shaft to cause it to rotate; in combination with the foregoing, structure including,

(a) a power piston having two elements secured to one another at abutting ends, outer ends of the elements forming piston heads,

(b) a crank shaft having a single crank pin journalled 6 in the abutting ends of the power piston elements, the crank shaft also having two aligned crank pins,

(c) the charge piston being an assembly having two elements interconnected by spaced slide blocks secured to the said elements, outer ends of the elements forming piston heads,

(i) the spaced slide blocks having horizontally aligned hearings in which the two aligned crank pins rotate,

(ii) transversely spaced guides of which the blocks are slideable, so constructed and arranged that the charge piston assembly is slideably supported by the blocks and by the power piston,

(d) an extension of the crank shaft having a pinion secured thereto the pinion being eccentric with respect to axes of the two aligned crank pins,

(e) a ring gear having internal teeth thereof in engagement with teeth of the pinion, the ring gear being secured to the output shaft which shaft is journalled in an end wall of a housing of the engine,

(f) an extension of the crank shaft remote from the piston having an eccentric thrust ring rotatable in an end portion concentric with the drive shaft and mounted for rotation in a concentric housing element, the thrust ring having openings,

(g) a carburetor secured to a housing end wall opposite the end wall aforesaid, and port means, coopcrating with motion of the piston, to admit carbureted fuel through the thrust ring openings, to passages communicating with the cylinders for charging compression power and exhaust strokes of the pistons.

2. Structure as defined in claim 1, the slide blocks being spaced apart by a distance such that opposing edges thereof are only slightly greater than the width of the power pistons, the said edges being recessed to receive webs of the crank.

3. An internal combustion engine as defined in claim 2 wherein,

(a) teeth of the pinion are provided only on an outer peripheral edge thereof, the teeth having a pitch circle,

(b) an inner edge of the pinion having a circular flange of outside diameter equal to that of the pitch circle and aligned therewith,

(c) a counterweight having concave semi-circular inner wall cooperating with an outer surface of the flange, and semi-circular outer wall concentric with the drive shaft and rotatable of housing within correspondingly shaped circular recess thereof,

(d) a similarly constructed and arranged counterweight cooperating with the eccentric thrust ring and the concentric housing element.

4. Structure as set forth in claim 3, a chamber being formed at the intersection of the paths of reciprocation,

(a) the power cylinders having a liner extending through the chamber,

(i) the liner having side openings providing access toh the chamber for rotating webs of the crank s aft,

(ii) and having encircling rows of spaced ports in register with the ports aforesaid.

5. Structure as defined in claim 4 wherein; a passage extends within a wall of a cylinder to an outlet communicating with a compression space of the cylinder.

6. Structure as defined in claim 3 wherein, the pistons have equal reciprocation.

7. Structure as defined in claim 5 wherein each piston has equal reciprocation referred to the intersection of the reciprocating paths.

References Cited UNITED STATES PATENTS 2,844,040 7/1958 Bancroft 123-55 MARK NEWMAN, Primary Examiner. WENDELL E. BURNS, Examiner. 

1. AN INTERNAL COMBUSTION ENGINE HAVING A POWER PISTON RECIPROCATING WITHIN ALIGNED POWER CYLINDERS, A CHARGE PISTON RECIPROCATING WITHIN ALIGNED CHARGE CYLINDERS, PATHS OF THE RECIPROCATING WITHIN ALIGNED CHARGE CYLINMUTUALLY PERPENDICULAR, AN OUTPUT SHAFT HAVING AN AXIS, THE POWER PISTON BEING OPERATIVELY CONNECTED TO THE OUTPUT SHAFT TO CAUSE IT TO ROTATE; IN COMBINATION WITH THE FOREGOING, STRUCTURE INCLUDING, (A) A POWER PISTON HAVING TWO ELEMENTS SECURED TO ONE ANOTHER AT ABUTTING ENDS, OUTER ENDS OF THE ELEMENTS FORMING PISTON HEADS, (B) A CRANK SHAFT HAVING A SNGLE CRANK PIN JOURNALLED IN THE ABUTTING ENDS OF THE POWER PISTON ELEMENTS, THE CRANK SHAFT ALSO HAVING TWO ALIGNED CRANK PINS, (C) THE CHARGE PISTON BEING AN ASSEMBLY HAVING TWO ELEMENTS INTERCONNECTED BY SPACED SLIDE BLOCKS SECURED TO THE HEAD ELEMENTS, OUTER ENDS OF THE ELEMENTS FORMING PISTON HEADS, (I) THE SPACED SLIDE BLOCKS HAVING HORIZONTALLY ALIGNED BEARINGS IN WHICH THE TWO ALIGNED CRANK PINS ROTATE, (II) TRANSVERSELY SPACED GUIDES OF WHICH THE BLOCKS ARE SLIDEABLE, SO CONSTRUCTED AND ARRANGED THAT THE CHARGE PISTON ASSEMBLY IS SLIDEABLY SUPPORTED BY THE BLOCKS AND BY THE POWER PISTON, (D) AN EXTENSION OF THE CRANK SHAFT HAVING A PINION SECURED THERETO THE PINION BEING ECCENTRIC WITH RESPECT TO AXES OF THE TWO ALIGNED CRANK PINS, (E) A RING GEAR HAVING INTERNAL TEETH THEREOF IN ENGAGEMENT WITH TEETH OF THE PINION, THE RING GEAR BEING SECURED TO THE OUTPUT SHAFT WHICH SHAFT IS JOURNALLED IN AN END WALL OF A HOUSING OF THE ENGINE, (F) AN EXTENSION OF THE CRANK SHAFT REMOTE FROM THE PISTON HAVING AN ECCENTRIC THRUST RING ROTATABLE IN AN END PORTION CONCENTRIC WITH THE DRIVE SHAFT AND MOUNTED FOR ROTATION IN A CONCENTRIC HOUSING ELEMENT, THE THRUST RING HAVING OPENINGS, (G) A CARBURETOR SECURED TO A HOUSING END WALL OPPOSITE THE END WALL AFORESAID, AND PORT MEANS, COOPERATING WITH MOTION OF THE PISTON, TO ADMIT CARBURETED FUEL THROUGH THE THRUST RING OPENINGS, TO PASSAGES COMMUNICATING WITH THE CYLINDERS FOR CHARGING COMPRESSION POWER AND EXHAUST STROKES OF THE PISTONS. 